The light beams generated by laser systems generally have a shape and spatial intensity distribution dictated by intrinsic characteristics related to the light-generating process and geometry of the laser. Typically, the raw light beam emitted from a laser has an elliptical shape or footprint in a plane transverse to its propagation axis, with a Gaussian irradiance distribution that peaks at its center and gradually fades towards the outer edges. For many applications, however, there is a need for converting a Gaussian beam into a flat-top beam, or more generally, into a beam with a different energy distribution and/or shape.
For example, in imaging applications a uniform light beam is preferred to produce good quality images while minimizing the fixed pattern noise caused by background information. Furthermore, when the energy of the light source is limited there is a need to concentrate as much energy as possible in a given area.
In another example, in laser material processing, there is a need for concentrating all the energy carried by an optical beam into a given shape such as a square, a circle or other given shapes. In this case there is a need for very weak absorption of the energy, hence the choice of a design based on reflective optics to limit the energy absorbed by the optics and maximize the energy that can be used to perform material processing.
There remains a need in the field for a device that allows a transformation of the spatial intensity distribution of a light beam while providing at least some of the beam characteristics mentioned above.